When yarn is rewound on a bobbin winding machine from a cop-wound delivery bobbin to a take-up bobbin, the yarn oscillates in a balloon shape when being drawn off the delivery bobbin and in addition performs a lengthwise motion like that of the spinning rail of a ring spinning machine because of the truncated cone-like deposit of the yarn on the yarn package by the spinning rail on the spinning frame. On the topmost end of the delivery bobbin, the yarn always wanders from the tube to the exterior circumferential yarn surface, in the course of which the balloon diameter changes from narrow to wide. The yarn moves with the greatest speed at the circumferential surface of the delivery bobbin and therefore forms the most distended balloon.
The yarn oscillating in a balloon shape has an effect on the force to be provided for pulling the yarn off the delivery bobbin. Balloons which oscillate particularly extensively exert a great tensile force on the yarn. For this reason attempts have been made for some time to exert an effect on the behavior of the yarn being unwound off the delivery bobbin.
While the intention initially was to suppress the formation of the balloon altogether, as disclosed in German Published, Examined Patent Application DE-AS 11 78 337 and Swiss Patent 362 350, later attempts tried to have an effect on the shape of the balloon, as disclosed in U.S. Pat. No. 3,718,296.
With increasing winding speeds, the influence on the balloon formation as described in the mentioned references loses its effect. While winding speeds of 200 to 500 meters had been considered to be great progress at the time these suggestions were made, currently conventional winding speeds already exceed 1500 meters per minute. The danger that loops can be withdrawn from the cop-wound delivery bobbins at these high speeds is therefore considerably greater. Loops are always generated when one or more yarn windings are withdrawn as a whole from the yarn package without a yarn turn being unwound by means of the yarn moving around the circumference of the yarn package. If such yarn loops encounter so-called "balloon breakers", interlacing of the yarn typically occurs and the yarn breaks.